I know, the title sounds incredibly funny - it actually was just like that and it truly was funny. I wasn't actually sleeping, just waiting using 'T' and I got disturbed by...Vivec. At least it looked exactly like him and it maybe was using his spell, although the spell was quite weak, so I'm not sure. But what was even more funny, the crazy Vivec was making werewolf noises. Does anyone have the same experience? I'm guessing it has to be bug in one mods I'm using, because I've never experienced this in a game earlier - not in this, not with any of my previous characters.

//One more thing, I didn't get a chance to check the body of whatever it was, because it disappeared right as I killed it.

This is definitely a mod.
I'll move it to the Mod forum and we can track down which mod does this. I've never heard of any mod that made Vivec-werewolves run around, but you never know.